1. Field of the Invention
The present invention is directed to linear ionizing bars and other corona discharge based ionization systems, processes and apparatus that use gas flow to direct charge carriers to a target. The invention is particularly useful in (but not limited to) Flat Panel Display (FPD) industrial applications. Accordingly, the general objects of the invention are to provide novel systems, methods and apparatus of such character.
2. Description of the Related Art
Conventional static neutralization systems are usually composed of: (1) a bar type ionization cell having a group of pointed emitters and non-ionizing reference electrode(s); (2) a clean gas supply system having a group of jet type nozzles surrounding each ion emitter and connected to an gas channel; and (3) a control system with an AC or pulsed AC high voltage power supply connected to the ionization cell.
Charge neutralization may entail neutralization of large charged objects at relatively close distances and at rapid throughput rates. For example, the front and back of glass panels having a length and a width exceeding 3000 mm may need to be charge-neutralized wherein the distance between an ionizing bar(s) and the display panels usually ranges from 50-100 mm up to 1000 mm or more, and wherein the display panels are transported at high speeds using robotics systems.
The use of traditional charge-neutralization ionizing bars of the type described above presents several deficiencies/drawbacks/limitations in trying to satisfy the above-described demanding requirements for charge neutralization of the FPD industry. These deficiencies may include:
The high cost of operating and maintaining traditional ionization cells, including the cost of high clean dry air (CDA) or nitrogen gas consumption during operation;
Insufficient cleanliness of the ionized gas stream because the higher quality of high resolution flat panel displays requires low or no particle emission (at least no particles larger than 0.1 micron) from the ion emitter(s); and
Unacceptably long discharge times for electrostatic charges because display panel throughput rates demand higher charge neutralization efficiency than has been heretofore available.
Charge neutralizing bars with linear ionizers (ionizing cells comprising long thin wire(s) as emitter(s)/electrode(s)) have been suggested in (1) U.S. Pat. No. 7,339,778, entitled “Corona Discharge Neutralizing Apparatus”; (2) U.S. Pat. No. 8,048,200, entitled “Clean Corona Gas Ionization For Static Charge Neutralization”; and (3) U.S. Patent Application Publication US 2007/0138149. U.S. Pat. No. 7,339,778, entitled Corona Discharge Static Neutralizing Apparatus, and issued on Mar. 4, 2008 is hereby incorporated by reference in its entirety. U.S. Pat. No. 8,048,200, entitled Clean Corona Gas Ionization For Static Charge Neutralization, and issued on Nov. 1, 2011 is also hereby incorporated by reference in its entirety. Further ionizing bars with wire emitters are currently produced by AB Liros Electronic of Malmö, Sweden and/or Liros Electronic of Hamburg, Germany using the following product names: standard series ionizers and/or SER series ionizing tubes.
Common problems encountered by the use of stretched wire emitter ionizers (linear ionizers) have been solved with the various innovations presented in U.S. patent application Ser. No. 13/438,538 filed Apr. 3, 2012 and entitled “MULTI-SECTIONAL LINEAR IONIZING BAR AND IONIZATION CELL” (now U.S. Pat. No. 8,492,733). However, additional refinements that further improve functionality are still possible and desirable.